1. Field of the Invention
The present invention relates to an optical system, especially to an optical system which is used in a chassis of a scan device to decrease a thickness of the chassis and further to decrease a volume of the scan device.
2. Description of the Prior Art
An image-processing device is known which makes copies by employing a so-called electro-photographic system. In an image processing device such as an image scanner, reflected light from an original irradiation by an illuminating optical system focuses an image on a light receiving element such as a CCD (Charge Coupled Device) sensor through a reduction optical system. The optical image corresponding to the image of the original is converted into a series of electrical image signals.
On the other hand, in a color image processing device, the reflected light from the original is focused on the light receiving element through color separation filters respectively corresponding to a particular color, and then, a plurality of optical images each corresponding to these colors are converted to a series of electrical image signals.
Generally, the above color image processing device is arranged to read the image signals corresponding to three primary colors, i.e. red(R), green (G), and blue(B); and to selectively locate one of three kinds of filters in an optical path of the reflecting light from the original. An image is realized on the light-receiving element according to the located filter. An ND filter also is employed as well as three color filters for regulating an optical length and an intensity of light. Therefore, four kinds of filters are selectively inserted in the optical path.
In the scan device, light usually passes through a complex optical path to be transmitted from the light source to the light-receiving element. Therefore, how to arrange a better optical path in the scan device is an important topic. The international technologies (referring to Sheng, U.S. Pat. No. 6,144,475 or Hama, U.S. Pat. No. 5,033,821) has disclosed a lot of optical paths by using different optical systems to make light transmit from the light source to the light-receiving element and to transform original papers or figures to become image signals. But the optical paths, which is arranged by the optical systems of the traditional technologies, still needs more space to make light transmit from the light source to the light-receiving element successfully. Therefore, a thickness of the chassis is thicker to provide enough space for optical paths, which is arranged by the optical systems of the traditional technologies. This condition will cause a thickness of the chassis not to be decreased and then a volume of the scan device is also not decreased. Following above descriptions, when a volume of the scan device is needed to be smaller and smaller, the traditional optical system, which cannot decrease the thickness of the chassis and further cannot decrease the volume of the scan device, has not conformed to needs of users.
In accordance with the background of the above-mentioned invention, the traditional optical systems still need more space to make light transmit from the light source to the light-receiving element and cannot decrease the volume of the scan device successfully. The present invention provides an optical system using in the scan device to decrease a thickness of a chassis by using five reflecting mirrors, which are assembled in the chassis, and adjusting a location and an angle of each reflecting mirror to arrange a optical path, wherein one of the five reflecting mirrors passes through two times reflecting processes.
The further object of the present invention is to decrease a volume of a chassis by using five reflecting mirrors, and adjusting a location and an angle of each reflecting mirror to arrange a optical path, wherein one of the five reflecting mirrors passes through two times reflecting processes.
In accordance with the present invention, the present invention provides an optical system using in the scan device to decrease a thickness of a chassis by using five reflecting mirrors, which are assembled in the chassis, and adjusting a location and an angle of each reflecting mirror to arrange a optical path, wherein one of the five reflecting mirrors passes through two times reflecting processes. The chassis of the present invention is assembled in the chassis and a scanning plate is assembled on the chassis in the first direction of the first axis, wherein the first direction of the first axis is vertical to the scanning plate. When using the scanning device, a cover board is placed on the scanning plate in the first direction of the first axis. The light, which is shot by the chassis and passes through the scanning plate, is reflected back to the chassis by the original. The chassis comprises a light source, a light-receiving element, the first reflecting mirror, the second reflecting mirror, the third reflecting mirror, the fourth reflecting mirror, and the fifth reflecting mirror. There is the first angle between the second direction of the second axis, which is parallel to a surface of the second reflecting mirror, and the third direction of the third axis, which is parallel to a surface of the third reflecting mirror. The first angle is about 4xc2x0 to 15xc2x0. There is the second angle between the second direction of the second axis and the first direction of the first axis and the second angle is about 0xc2x0 to 5xc2x0. When the scan device is started to proceed with a scanning process, the first light is shot from the light source. After the first light passing through the scanning plate and reaching to the original, the first light is reflected by using the original to become the second light, which towards to the first reflecting mirror. After the first reflecting mirror receiving the second light, the second light is reflected by using the first reflecting mirror to become the third light, which towards to the second reflecting mirror. After the second reflecting mirror receiving the third light, the third light is reflected by using the second reflecting mirror to become the fourth light, which towards to the third reflecting mirror. After the third reflecting mirror receiving the fourth light, the fourth light is reflected by using the third reflecting mirror to become the fifth light, which towards to the second reflecting mirror. After the second reflecting mirror receiving the fifth light, the fifth light is reflected by using the second reflecting mirror to become the sixth light, which towards to the fourth reflecting mirror. After the fourth reflecting mirror receiving the sixth light, the sixth light is reflected by using the fourth reflecting mirror to become the seventh light, which towards to the fifth reflecting mirror. After the fifth reflecting mirror receiving the seventh light, the seventh light is reflected by using the fifth reflecting mirror to become the eighth light, which towards to the light-receiving element. In the operating process of the optical system of the present invention, the second reflecting mirror is a mirror which passes through two times reflecting processes. When the light-receiving element receiving the eighth light, the original, which are placed on the scanning plate, are transformed to become the image signals. The image signals are provided for users to proceed with following procedures. The optical system of the present invention can also decrease a thickness of the chassis and a volume of the scan device.